Re: [PATCH] gpiolib: fix allocation of mixed dynamic/static GPIOs

[Christophe Leroy]

Le 27/04/2023 à 08:00, Andy Shevchenko a écrit :
> On Thu, Apr 27, 2023 at 8:40 AM Christophe Leroy
> <christophe.leroy@xxxxxxxxxx> wrote:
>>
>>
>>
>> Le 27/04/2023 à 00:03, Andreas Kemnade a écrit :
>>> [Vous ne recevez pas souvent de courriers de andreas@xxxxxxxxxxxx. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
>>>
>>> If static allocation and dynamic allocation GPIOs are present,
>>> dynamic allocation pollutes the numberspace for static allocation,
>>> causing static allocation to fail.
>>> Enfore dynamic allocation above GPIO_DYNAMIC_BASE.
>>
>> Hum ....
>>
>> Commit 7b61212f2a07 ("gpiolib: Get rid of ARCH_NR_GPIOS") was supposed
>> to enforce dynamic allocation above GPIO_DYNAMIC_BASE already.
>>
>> Can you describe what is going wrong exactly with the above commit ?
> 
> Above commit only works to the first dynamic allocation, if you need
> more than one with static ones present it mistakenly will give you a
> base _below_ DYNAMIC_BASE.

Ah right, that needs to be fixed.

> 
> However, this change is just PoC I proposed, the conditional and
> action should be slightly different to cover a corner case, when
> statically allocated chip overlaps the DYNAMIC_BASE, i.e. gdev->base <
> DYNAMIC_BASE, while gdev->base + gdev->ngpio >= DYNAMIC_BASE.
> 

Yes you are right, that's gdev->base + gdev->ngpio that should be checked.

Christophe